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Watch your weight if you’re trying to conceive, or else your kids might pay for it

Research has shown that weight can affect fertility in both men and women. A new study published in Cell Metabolism dug a little deeper and discovered how a father’s weight may affect his children’s predisposition to obesity.

Researchers from the Novo Nordisk Foundation Center for Basic Metabolic Research studied the ejaculate of 13 slim and 10 obese men. They also studied the sperm of six men before, in the midst of, and after gastric bypass (a surgical weight-loss procedure).

Researchers discovered an average of 4-5,000 changes to the individual’s sperm cell DNA among the men who underwent the procedure, including areas that affect the appetite of the child that sperm could produce. The obese and slim groups also showed different epigenetic markers in genome regions that control appetite. Changes to how genes are expressed can be caused by environment and lifestyle. While the study did not focus on the differences in effects on sperm DNA between natural weight loss and surgical methods, it was noted that as little as six weeks worth of weight loss could cause epigenetic changes.

Associate Professor Romain Barrès, one of the study’s authors, pointed out in a statement, “We certainly need to further examine the meaning of these differences; yet, this is early evidence that sperm carries information about a man’s weight. And our results imply that weight loss in fathers may influence the eating behavior of their future children,”

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Dr. Ida Donkin, another author of the study, told Medical Daily, “Weight-loss — no matter the tool you use to obtain it — will change the information of the sperm cells and most likely influence the development and risk of disease of your children.”

The scientists believe this tendency for weight to affect offspring at the time of conception is a product of humanity’s harsh early years, where being large was a benefit to survival. A heavier person has stored fat for lean times. “It’s only recently that obesity is not an advantage,” said Barrès, He also referenced a study showing how famine in a small Swedish village correlated with the risk of cardiometabolic diseases in the sufferer’s grandchildren. “We have identified the molecular carrier in human gametes that may be responsible for this effect,” he said.

Minute differences in RNA expressions and DNA methylation patterns proved that weight loss can change the epigenetic instructions of spermatozoa, and thence the development of an embryo and the child into which it grows. “Discovering that lifestyle and environmental factors, like a person’s nutritional state, can shape the information in our gametes and thereby modify the eating behavior of the next generation is, to my mind, an important find,” Barrès said.

This study negates the idea that the info carried in gametes can’t be changed. “Today we know that children born to obese fathers are predisposed to developing obesity later in life, regardless of their mother’s weight.” Dr. Donkin said. What this means is fathers-to-be need to be just as conscious of their health habits as mothers — and that’s from when couples begin trying to conceive.